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United States Patent |
5,268,151
|
Reed, deceased
,   et al.
|
December 7, 1993
|
Apparatus and method for generating ozone
Abstract
A corona discharge generator is disclosed, and includes a central tube of
electrically conducting material circumscribed by a glass tube having an
electrically conducting coating on its exterior surface and being sealed
to the exterior surface of the central tube at opposites ends of the glass
tube. The central tube is blocked within the longitudinal extent of the
glass tube, and provided with holes between the interior of the central
tube and the annular enclosure formed between the central tube and the
glass tube, toward the opposite ends of the glass tube. Oxygen-containing
gas flows along the central tube, out a first hole or holes to the
enclosure, along the enclosure and back through one or more holes into the
central tube on the downstream side of the blockage. A pulsed electrical
signal is applied to the two tubular electrodes to effect a corona
discharge within the enclosure, thereby producing ozone. An electrical
circuit is disclosed to provide such a pulse signal of variable frequency
whereby the rate of production of ozone may be selected.
Inventors:
|
Reed, deceased; Bruce A. (Visalia, CA);
Randall; Donald R. (Clovis, CA)
|
Assignee:
|
Ozone Equipment, Inc. (Houston, TX)
|
Appl. No.:
|
595961 |
Filed:
|
October 12, 1990 |
Current U.S. Class: |
422/186.16; 422/186.18 |
Intern'l Class: |
B01J 019/12 |
Field of Search: |
422/186.15,186.16,186.18
|
References Cited
U.S. Patent Documents
3800210 | Mar., 1974 | Caussin | 321/9.
|
3905920 | Sep., 1975 | Botcharoff | 250/536.
|
3942093 | Mar., 1976 | Lowther | 321/45.
|
4016060 | Apr., 1977 | Lowther | 204/176.
|
4283291 | Aug., 1981 | Lowther | 250/536.
|
4320301 | Mar., 1982 | Kogelschatz | 422/186.
|
4504445 | Mar., 1985 | Walz | 422/186.
|
4603031 | Jul., 1986 | Gelbman | 422/186.
|
4869881 | Sep., 1989 | Collins | 422/186.
|
4966666 | Oct., 1990 | Waltonen | 204/164.
|
4988484 | Jan., 1991 | Karlson | 422/186.
|
5091069 | Feb., 1992 | Hendrickson et al. | 204/176.
|
5147614 | Sep., 1992 | Conrad | 422/186.
|
Primary Examiner: Walsh; Donald P.
Assistant Examiner: Jenkins; Daniel
Attorney, Agent or Firm: Sroufe, Zamecki, Payne, Lundeen
Claims
What is claimed:
1. Apparatus for generating ozone, including an electrical circuit
providing a signal for application across electrodes for generation of
ozone, comprising:
a. an output transformer, stepped up to provide a high voltage output
signal across the secondary winding of the transformer in response to
variation in a relatively low voltage dc signal across the primary winding
of the transformer;
b. a power supply for applying such a relatively low voltage dc signal
across the primary winding;
c. a silicon control rectifier in parallel with the primary winding of the
transformer for providing a short across the primary winding of the
transformer when the silicon control rectifier is enabled; and
d. a variable frequency oscillator for producing a pulsed gating signal for
periodically enabling the silicon control rectifier so that the primary
winding of the transformer is periodically shorted, thereby producing a
pulsed output signal from the secondary winding of the transformer, with
the frequency of the pulses being set by the frequency of the oscillator.
2. Apparatus as defined in claim 1 further comprising:
a. a central tube of electrically conducting material;
b. a second tube of generally non-electrically conducting dielectric
material, of greater diameter than the central tube and positioned coaxial
therewith, so that the second tube generally surrounds the central tube;
c. a cover comprising electrically conducting material positioned on the
outside of the second tube;
d. seals positioned within each end of the second tube, comprising
electrically insulating material, sealing the interior surface of the
second tube to the exterior surface of the central tube toward each end of
the second tube, whereby an annular enclosure is formed between the
exterior surface of the central tube and the interior surface of the
second tube, and between the two seals; and
e. one or more passages through the wall of the central tube located toward
opposite ends of the second tube and within the longitudinal extent of the
annular enclosure, and a blockage within the central tube positioned
between the two sets of passages;
f. a fluid flow path thus formed along the interior of the central tube to
the first passage, therethrough to the annular enclosure and on to the
second passage, and therethrough into the interior of the central tube on
the opposite side of the blockage.
3. Apparatus as defined in claim 2 wherein the conductive cover comprises a
coating of conductive material on the exterior surface of the second tube.
4. Apparatus as defined in claim 2 further comprising a housing generally
circumscribing the second tube and radially displaced therefrom.
5. Apparatus as defined in claim 2 wherein said second tube comprises a
glass tube.
6. Apparatus as defined in claim 1 wherein the output signal from the
transformer is connected to the central tube and the conductive coating
acting as electrodes, to apply an electric field across the enclosure
while oxygen is positioned therein, to produce ozone.
7. Apparatus as defined in claim 6 wherein the pulses of the electrical
signal output from the transformer are ac.
8. Apparatus as defined in claim 1 wherein the variation of the frequency
of the pulses output from the transformer affects the rate of production
of ozone.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to techniques for producing ozone. More
particularly, the present invention relates to methods and apparatus for
apply an appropriate electric field across an oxygen-containing atmosphere
to break oxygen molecules (O.sub.2) into atoms (O) which may then regroup
as ozone (O.sub.3). A high voltage signal is used to produce a corona
discharge between electrodes, within which oxygen-containing gas is
positioned, whereupon the above interaction occurs to produce ozone. Ozone
has many commercial and scientific uses including, for example,
disinfection, reduction of toxicity, odor control, organic oxidation and
removal, and removal of suspended solids.
2. Description of Prior Art
Various techniques are known for arranging the electrodes across which an
electrical signal is provided to produce ozone. One method of arranging
the electrodes is to provide parallel plates as electrodes. Another
general form of electrode arrangement involves a central wire serving as
one electrode and an outer cylindrical tube providing a second electrode.
Concentric tubular electrodes are also known.
Various known arrangements for producing ozone may employ circulation of
coolant fluid to overcome any excess heat generated in the process.
Additionally, a given electrode arrangement may be particular sensitive to
misalignment.
It is advantageous and desirable to provide an ozone generator whose
electrodes are relatively easily mutually oriented, and wherein the
orientation of the electrodes may be maintained without any difficulty. It
is further desirable and advantageous to provide an ozone generating
system which produces ozone efficiently with minimal heat generation, and
wherein the ozone may be generated relatively rapidly. Relative compact
size would also be a desirable feature of an ozone generator.
Additionally, the ability to easily vary the rate at which ozone is being
generated in a given flow of oxygen-containing gas, for example, is
another desirable feature. PG,4
SUMMARY OF THE INVENTION
The present invention provides an ozone generator including a central tube
of electrically conducted material surrounded by a second tube of
generally non-electrically conducting material, with the two tubes
positioned mutually coaxially. Seals are positioned toward the two ends of
the second tube, which may be shorter than the central tube, to seal the
interior surface of the second tube to the exterior surface of the central
tube. An enclosure is thus formed comprising the annular region between
the outer surface of the central tube and the inner surface of the second
tube, and between the two seals. Electrically conducting material covers
the outer surface of the second tube. Thus, two coaxial cylindrical
electrodes are formed comprising the central tube and the cover on the
outer surface of the second tube. An electrical signal may be applied
between these electrodes to produce a corona discharge within the annular
enclosure.
The central tube, which may be made of metal such as stainless steel,
features holes through the wall of the tube located toward opposite ends
of the second tube, generally just inside the enclosure from the positions
of the two seals. The longitudinal central passageway of the central tube
is blocked between the two positions of the holes; the blockage may be
generally located about midway of the longitudinal extent of the
enclosure. Thus, a flow passage for gas for use in the production of ozone
is formed, starting along the central passage of the central tube to the
first hole or holes at one end of the enclosure, through those holes into
the enclosure, along the enclosure toward the opposite end thereof and
through the holes at that opposite end back to the interior of the central
tube, thus, bypassing the blockage of the central passage of the central
tube. While the gas is in the enclosure, an electrical signal applied to
the electrodes may produce a corona discharge, converting oxygen within
the gas to ozone. The ozone flows out the passageway with whatever
non-ozone gas exists.
The second tube may be made of glass, and the conducting cover of the
second tube may be provided by an appropriate conducting material applied
as a coating to the exterior surface of the glass tube, for example.
The ozone generator may be enclosed, at least in part, in a protective
housing, with appropriate access to the two electrodes for application of
electric signals thereto, as well as access to the central passage of the
central tube at both ends of the central tube.
An electrical circuit may be provided for producing a high voltage pulsed
ac signal to be applied to the electrodes of the generator. The ac pulses
may be generated as output from a high voltage transformer. A dc voltage
may be placed across the primary winding of this transformer, which is
periodically shorted with the resulting ac pulse produced across the
secondary winding. A silicon control rectifier may be periodically enabled
to so short the primary winding of the transformer, with an oscillator
providing a gating signal to periodically enable the silicon control
rectifier. A variable frequency oscillator may be used to so control the
silicon control rectifier, thereby allowing the frequency of the high
voltage ac output pulses to be readily varied.
The present invention thus provides an ozone generating system, including a
corona discharge generator which may be constructed compactly and operated
at relatively high efficiency for production of ozone, and further
provides, in a preferred embodiment, an electrical circuit which produces
an output pulse signal for use in generating ozone whose frequency may be
readily adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of an ozone generator according to the present
invention;
FIG. 2 is a longitudinal cross section of the ozone generator of FIG. 1,
with the electrical terminals removed;
FIG. 3 is a schematic representation of an ozone generation system;
FIG. 4 is a diagram of an electrical circuit according to the present
invention for driving the ozone generator in FIGS. 1 and 2; and
FIG. 5 is another embodiment of an electrical circuit according to the
present invention for driving the ozone generator of FIGS. 1 and 2.
DESCRIPTION OF PREFERRED EMBODIMENTS
An ozone generator in the form of a corona discharge tube is shown
generally at 10 in FIGS. 1 and 2. A central metal tube 12 extends through
the center of the generator 10, and is surrounded by a glass second tube
14 of somewhat shorter length than the metal tube. Just inside each of the
two ends of the glass tube 14 is an annular packing 16. The two packings
16 serve to seal the interior surface of the glass tubing 14 to the
exterior surface of the metal tubing 12 to form an elongate, annular
enclosure, and to maintain the metal tube centered along the interior of
the glass tube, so that the two tubes are coaxial. The material of the
packings 16 is also an electrical insulator.
The combination of the metal tube 12 and the glass tube 14 is enclosed
within a tubular housing 18 which is approximately as long as the glass
tubing. The ends of the housing 18 are closed by caps 20 and 22, which may
be friction-fitted over the tube 18. The metal tube 12 is longer than the
glass tube 14 as well as the housing tube 18, and extends through
appropriate holes in the two end caps 20 and 22. The housing tube 18 and
housing end caps 20 and 22 are constructed of electrically insulating
material, such as polyvinylcholoride (PVC). The ends of the glass tube 14
abut the end caps 20 and 22 in the assembled configuration as illustrated
in FIG. 2.
The exterior surface of the glass tube 14 is covered by an electrical
conductor 24. Although the conductor 24 may be composed of a variety of
materials, the conductor may be readily constructed by coating the
exterior surface of the glass tube 14 with a graphite dispersion in liquid
which may be dried to a continuous, fairly uniform conductive coating.
Such a dispersion of colloidal graphite in water is sold under the
trademark "Aquadag" though other graphite dispersions are available.
The metal tube 12 serves as one electrode, and the conductive coating 24
serves as another electrode surrounding the first electrode of the metal
tube, and displaced therefrom by the radial distance between the exterior
surface of the metal tube and the interior surface of the glass tube 14,
and further by the thickness of the glass tube serving as an additional
dielectric. As discussed more fully hereinafter, application of an
appropriate voltage between the electrodes 12 and 24 produces a corona
discharge within the glass tube 14, exterior to the metal tube. An
electrical terminal 26 is shown in FIG. 1 clipped to the metal tube 12
beyond the end cap 22; another electrical terminal 28 may be clipped about
the glass tube 14 to make electrical contact with the conductive coating
24, and is accessed through an appropriate hole 30 in the housing tube 18.
An insulated electrical lead 32 is shown in FIG. 1 connected to the
clipped electrode 28. The aforementioned voltage may be applied to the
electrodes 12 and 24 by way of the terminals 26 and 28, respectively. The
insulating housing in the form of the tube 18 and caps 20 and 22 provides
a safety covering for the application of high voltages to the corona
discharge tube, while also providing means for safely handling and
mounting the corona discharge tube, for example. The exposed metal tube
electrode 12 may be maintained at electrical ground, for example.
To produce ozone with the generator 10, oxygen or oxygen-containing gas,
such as air, is introduced into the annular region between the exterior
surface of the metal tube electrode 12 and the interior surface of the
glass tube 14 wherein a corona discharge is formed. For this purpose, the
interior of the metal tube 12 is closed by a plug 34 at or about the
longitudinal center of the generator 10. The metal tube 12 is broken by
one or more holes 36 (three are shown) just to the inside of the location
of one of the packings 16. Similarly, the metal tube 12 is broken by one
or more holes 38 (three are shown) just inside the position of the other
packing 16 at the opposite end of the generator 10. Gas containing oxygen
is made to flow along the interior of the tube 12 and thereby enter the
generator 10 from one end thereof. The block 34 prevents the gas from
flowing straight through the metal tube 12. Consequently, the input gas
passes through the holes 36, for example, to the annular region between
the exterior surface of the metal tube 12 and the interior surface of the
glass tube 14. The gas then flows the length of this annular enclosure and
re-enters the interior of the metal tube 12 through the holes 38, on the
downstream side of the block 34. While the gas is within the enclosure
between the exterior surface of the metal tube 12 and the interior surface
of the glass tube 14, the aforementioned voltage may be applied to the
electrodes 12 and 24 to produce the corona discharge within the
oxygen-containing gas to effect the interaction which produces ozone. The
ozone exits the generator 10 through the holes 38 and the downstream
interior of the metal tube 12.
Since portions of the ozone generator 10 are exposed to ozone, materials
may be selected for the construction of the exposed portions of the
generator to eliminate, or at least minimize, any detrimental interactions
with ozone. The metal tube 12 may be stainless steel, and the packings 16
may be formed, for example, of an electronic grade silicone adhesive which
is both non-contaminating and relatively impervious to ozone. Such an
adhesive cures to a sufficiently rigid consistency to at least help
maintain the glass tube 14 positioned coaxially with the stainless steel
tube 12. The plug 34 may also be stainless steel, or some other material
which can both provide a gas-tight seal within the tube 12 and resist
attack by ozone.
A well-annealed glass may be chosen for the tube 14, for example. The well
known borosilicate glass commonly used in laboratory work and sold under
the trademark "Pyrex" may be used for this purpose, for example.
The generator 10 may be constructed in a variety of sizes, including
relatively small. For example, the generator 10 may be constructed with
the metal tube 12 extending for approximately one foot in length, and
extending five-sixteenth inch across. The glass tube 14 and surrounding
housing tube 18 may extend approximately nine and one-half inches in
length. The annular spacing between the metal tube 12 and the interior
surface of the glass tube 14 may, for example, be approximately
three-eighths inch with a glass tube approximately three-quarters of an
inch in outer diameter, for example. The interior diameter of the housing
tube 18, for example, may be one and one-half inches. With such
dimensions, the applied voltage to produce the corona discharge within the
generator may be on the order of ten to twenty thousand volts, for
example. The gas flow holes 36 and 38 may, for example, be on the order of
one-eighth inch in diameter.
A system for generating ozone is shown generally at 40 in FIG. 3, and
includes an ozone generator 42 which may be of the type illustrated in
FIGS. 1 and 2. Oxygen, or oxygen-containing gas, is made to flow into the
generator 42 as at 44, and ozone, or ozone-containing gas is output from
the generator at 46. The ozone generator 42 is operated, or driven, by an
input electrical signal, as at 48, to produce the discharge which effects
the production of the ozone.
A clean, relative dry stream of gas input at 44 to the generator 42 is
preferred for efficient production of ozone with little or no
contamination of the system. To achieve this condition, the input gas may
be appropriately treated. For example, gas, such as air, may be passed
through a first filter 50 as at 52 to generally clean the air by removing
particles therefrom. Such a particulate filter may include a mesh, or one
or more screens or the like, whose flow passages are sufficiently small to
stop particles down to some selected minimum size.
Output from the particulate filter 50 is directed to a compressor 54 of the
oilless type to drive the flow of gas along the system. For a generator of
the type illustrated in FIGS. 1 and 2 with the typical dimensions
discussed above, the output of the compressor 54 may typically have a flow
rate of six to eight cubic feet per minute, and a pressure of
approximately two atmospheres. The compressor itself need only be
one-sixth or one-third horsepower to supply one, or even several, such
sized ozone generators. Tubing utilized to conduct the gas flow leading up
to input to the generator 42 may be five-sixteenth or three-eighths inch
internal diameter for such sized generator.
Output flow from the generator 54 is directed to a second filter 56
designed to remove vapor, such as oil and/or water vapor, from the air,
for example. Such a filter may include a bed of brass pellets so that the
gas being filtered is exposed to a large surface area of brass. The
contaminate fluid collected by the filter 56 is permitted to drain as at
58. The gas is further dried in a drier 60 which includes a desiccant such
as activated charcoal or silica gel, for example. Additional filtering
and/or drying may be utilized as needed. The gas thus cleansed is input
into the generator 42 as at 44.
Input power (typically 115 volts at 60 Hz) is provided at 62 to a power
supply 64 whose generated signal is preferably able to be varied in
frequency, such as by a frequency converter or variable frequency
oscillator 66. The signal 48 input to the ozone generator 42 is taken
across the secondary of a high voltage transformer 68. As discussed more
fully below, the signal 48 may be in the form of a pulsed signal, with
each pulse in the form of a damped oscillating ac signal. The frequency of
the pulses may be varied to control the rate of ozone production, for
example.
With the pulse signal 48 applied to the corona discharge tube of the
generator 42, the gas flow through the generator emerges at 46 with a
concentration of ozone. Thereafter, the ozone may be utilized in a variety
of applications. In certain applications, the ozone or ozone-containing
gas, such as air, is preferably mixed with a liquid which may then be
readily conveyed and applied in a variety of ways, such as by spraying,
washing, soaking, etc.
To prevent any possible backflow of the ozone output 46 into the generator
42, a check valve 70 may be utilized in the output flow line as
illustrated in FIG. 3. For mixing with a liquid, the output of the check
valve 70 may be introduced into an injector 72. The liquid into which the
ozone is to be mixed is input at 74 to the injector 72. Within the
injector, the liquid flow line is constricted at the point of junction
with the gas inlet port. The resulting increased velocity of the liquid
passing the opening to the gas line provides a suction effect which draws
the ozone/gas into the liquid. Thereafter, the cross section of the flow
line for the gas/liquid combination is increased so that the flow velocity
of the output of the injector at 76 is reduced, possibly to that of the
input liquid flow velocity at 74. The output 76 of the injector 72 thus
comprises liquid with entrained ozone for application of the ozone as
desired.
The injector 72 may also include a check valve so that the external check
valve 70 serves as a back up. The check valves prevent moisture from
backing into the generator, for example, when the system is shut down so
that there is not enough fluid pressure to prevent liquid from getting
into the ozone generator.
The apparatus through which the ozone is conducted may be constructed from
materials selected for minimal or no detrimental interaction with ozone,
particularly the materials of the apparatus exposed to ozone directly, or
to ozone carried by other gas. Thus, the flow line from the generator 42
to the injector 72 may be stainless steel. If a flexible flow line is
required, tubing made from a corrosion resistant material, such as a vinyl
compound tubing sold under the trademark "Tygon," for example, may be
used.
An electrical power supply and triggering circuit for operating a corona
discharge ozone generator such as the generator 10 of FIGS. 1 and 2, and
which may be used in the system 40 as at 42, is shown in schematic at 80
in FIG. 4. Input power, such as 115 volts at 60 Hz, is applied to an input
transformer, or other inductor, 82 whose output is placed across a diode
bridge 84. The full-wave rectified, unfiltered dc voltage output of the
bridge 84 is applied, thorough a coupling capacitor 86, to the primary
winding of a high voltage output transformer 88. The output signal of the
circuit 80 is taken at 90 across the secondary winding of the output
transformer 88. The output signal 90 is obtained upon the collapse of the
voltage across the primary of the transformer 88 which is effected by the
shorting of the transformer primary by means of the silicon control
rectifier (SCR) 92. Application of a positive pulse to the gate of the SCR
92 enables the SCR, thus shorting the coupling capacitor 86 and the
primary of the output transformer 88.
The SCR 92 is operated by a relaxation oscillator comprising a unijunction
transistor 94, a resistor 96 and a capacitor 98. The relaxation oscillator
produces a short duration pulse due to current flowing through the
transistor 94 and the two current-limiting resistors 100 and 102. Cyclical
pulsing comes about due to the repeated charging and discharging of the
capacitor 98. The resistors 104 and 106 set the voltage at which the
relaxation oscillator operates.
On a periodic basis, determined by the frequency of operation of the
relaxation oscillator which, in turn, is determined by the values of the
resistor 96 and the capacitor 98, the SCR 92 is periodically enabled to
short the primary of the output transformer 88. The collapsing signal
across the transformer primary produces an output signal across the
transformer secondary. The typical applied voltage to the primary may be
on the order of 100 or so volts; however, the output signal on the stepped
up secondary of the transformer may be on the order of 15,000 volts to
20,000 volts, for example. The output signal 90 is in the form of pulses,
with a pulse produced each time the transformer primary is so shorted
through the SCR 92. However, due to the self inductance of the transformer
88, the pulse experiences a ringing effect. Thus, the pulse form is
generally a decreasing ac signal whose envelope shape is generally
exponential, and which is symmetric around zero volts.
Another version of an electrical circuit to drive a corona discharge ozone
generator, such as that illustrated in FIGS. 1 and 2 and shown at 42 in
FIG. 3, is illustrated generally at 110 in FIG. 5. In the circuit 110, the
frequency of the pulses of the output signals of the circuit may be
readily varied.
In the circuit 110, input power (115 volts at 60 Hz, for example) is
applied to an input transformer 112; the output of the transformer is
applied across a diode bridge 114 to provide fullwave rectified, but
unfiltered, dc output. The bridge output signal is applied through a
coupling capacitor 116 to the primary winding of a high voltage output
transformer 118. Again, collapse of the dc signal across the primary
winding of the output transformer 118 produces a high voltage (on the
order of 15,000 to 20,000 volts, for example) pulse output signal 120 from
the transformer secondary for application across the electrodes of a
corona discharge ozone generator. An SCR 122 is positioned to short the
capacitor 116 and the primary of the transformer 118 periodically as an
enabling pulse is applied to the gate of the SCR. A variable frequency
relaxation oscillator, comprising an integrated circuit 124 and a voltage
divider including a variable resistor 126 and a fixed resistor 128, and a
capacitor 130 provides the pulsing signal at 132 to the SCR 122. The
operating voltage for the integrated circuit 124 is applied at 134; the
voltage divider resistors 126 and 128 are connected to control voltage
inputs to the integrated circuit. Variation of the variable resistor 126
selectively varies the frequency of the output pulses 132 of the
integrated circuit 124 and, therefore, the frequency of pulsing of the
high voltage circuit output 120.
Typically the SCR used in either of the two circuits of FIGS. 4 or 5 may be
that identified as 2N3899, the unijunction transistor of FIG. 4 may be a
2N2646, and the integrated circuit used to produce the variable frequency
pulsing of the circuit of FIG. 5 may be that commonly referred to as
LM555.
In the corona discharge ozone generator, ozone is generated during
application of the high voltage pulse between the electrodes of the
generator. For a given rate of flow of oxygen-containing gas into the
corona discharge region of the ozone generator, the amount of ozone that
is generated in a given period of time increases with the portion of that
time that the pulses are in existence. Consequently, by increasing the
pulse frequency produced by the circuit of FIG. 5, the rate of ozone
production may be increased.
The present invention thus provides a corona discharge-type ozone generator
which may be constructed of relatively compact size. Further, the ozone
generator of FIGS. 1 and 2 can accommodate a relatively rapid flow of gas
therethrough to increase the efficiency of production of ozone and, at the
same time, minimize the heating of the device. Consequently, no coolants
need be applied to the ozone generator to overcome any excess heat
generation.
The present invention further provides electronic circuitry for driving the
ozone generator with pulses structured with ac, again to provide ozone
generation with increased efficiency. Further, in one embodiment of the
electronic circuitry, the frequency of pulses to the ozone generator may
be readily varied to selectively adjust the rate of production of ozone in
the generator, even for a fixed flow of gas therethrough.
The foregoing disclosure and description of the invention is illustrative
and explanatory thereof, and various changes in the method steps as well
as in the details of the illustrated apparatus may be made within the
scope of the appended claims without departing from the spirit of the
invention.
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